The LT3685 is an adjustable frequency (200kHz to 2.4MHz) monolithic step-down switching regulator that accepts input voltages up to 38V operating and 60V maximum. It features an internal overvoltage protection circuit that turns off the power switch when VIN is above 38V typical (36V minimum) which then allows the part to safely withstand 60V transients. Current mode topology is used for fast transient response and good loop stability. The high operating frequency of the LT3685 allows the use of small, low cost inductors and ceramic capacitors resulting in low output ripple while keeping total solution size to a minimum. The low current shutdown mode reduces input supply current to less than 1μA while a resistor and capacitor on the RUN/SS pin provide a controlled output voltage ramp (soft-start). A power good flag signals when VOUT reaches 86% of the programmed output voltage. The LT3685 is available in 10-Pin MSOP and 3mm × 3mm DFN packages with exposed pads for low thermal resistance.
The LT3685 is an adjustable‑frequency step‑down switching regulator that operates from 3.6 V to 36 V input and can handle up to 60 V transients. It delivers up to 2 A output current, offers a wide output voltage range (0.79 V to 20 V), and includes features such as over‑voltage lockout, a power‑good flag, and a soft‑start capability.
The device is offered in 10‑lead MSOP and 3 mm × 3 mm DFN packages with exposed pads for thermal performance. Pin functions, electrical characteristics, and typical performance curves are detailed for design reference.
| Input Voltage Range | 3.6 V to 36 V |
|---|---|
| Maximum Output Current | 2 A |
| Adjustable Switching Frequency | 200 kHz to 2.4 MHz |
| Quiescent Current (Shutdown) | < 1 pA |
| Feedback Reference Voltage | 0.790 V |
| Output Voltage Range | 0.79 V to 20 V |
| Power‑Good Flag | Enabled when FB reaches 86 % of Vout |
| Package Options | 10‑lead MSOP, 3 mm × 3 mm DFN |
The regulator operates with a minimum input voltage of 3.6 V.
In shutdown mode the input current is less than 1 pA.
The device is offered in a 10‑lead MSOP package and a 3 mm × 3 mm DFN package with an exposed pad.
The internal feedback reference voltage is 0.790 V.